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Symptoms and Control Methods of White Root Rot in Cherry Blossoms

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Symptoms White root rot has become increasingly severe in damaging garden trees in recent years, especially in cherry blossoms. The disease mainly occurs on the roots of trees. After the fibrous roots are infected, it gradually spreads to the lateral roots and the main root. Its characteristic symptom is a layer of grayish-white silky mesh covering the diseased roots; afterward the roots rot, causing the cortex to separate, and the root absorption function is severely lost. In mild cases, the cherry blossom grows poorly and the tree vigor weakens; in severe cases, it causes death. Pathogen and disease pattern The pathogen is Dematophora necatrix Harting, and its sexual stage is the rare Rosellinia necatrix. This fungus also infects many plants such as poplar, willow, ginkgo, paulownia, wintersweet, crabapple, mountain peach, tea, spruce, cedar, flowering almond, tree peony and Chinese peony. The pathogen overwinters as mycelium, rhizomorphs and sclerotia in the soil or in diseased plant residues. White root rot is a soil-borne root disease, and its infection cycle is not obvious. In April-May of the following year, under conditions of abundant rain and moist soil, the rhizomorphs spread and transmit through the soil. The pathogen can invade through wounds and lenticels on young roots. Generally, trees planted in poorly drained, weak-growing and waterlogged low-lying land are more severely affected. In the Beijing area, white root rot occurs severely from July to August; later, small black dots, which are the pathogen's perithecia, grow on the mycelial membrane.

Symptoms White root rot has become increasingly severe in damaging garden trees in recent years, especially in cherry blossoms. The disease mainly occurs on the roots of trees. After the fibrous roots are infected, it gradually spreads to the lateral roots and the main root. Its characteristic symptom is a layer of grayish-white silky mesh covering the diseased roots; afterward the roots rot, causing the cortex to separate, and the root absorption function is severely lost. In mild cases, the cherry blossom grows poorly and the tree vigor weakens; in severe cases, it causes death.

Pathogen and disease pattern The pathogen is Dematophora necatrix Harting, and its sexual stage is the rare Rosellinia necatrix. This fungus also infects many plants such as poplar, willow, ginkgo, paulownia, wintersweet, crabapple, mountain peach, tea, spruce, cedar, flowering almond, tree peony and Chinese peony. The pathogen overwinters as mycelium, rhizomorphs and sclerotia in the soil or in diseased plant residues. White root rot is a soil-borne root disease, and its infection cycle is not obvious. In April-May of the following year, under conditions of abundant rain and moist soil, the rhizomorphs spread and transmit through the soil. The pathogen can invade through wounds and lenticels on young roots. Generally, trees planted in poorly drained, weak-growing and waterlogged low-lying land are more severely affected. In the Beijing area, white root rot occurs severely from July to August; later, small black dots, which are the pathogen's perithecia, grow on the mycelial membrane.

Integrated control

(1) Strengthen maintenance and management Pay attention to drainage in low-lying areas after rain. Fertilize reasonably, especially by increasing the application of compound fertilizer, to promote strong root growth. When planting new greenery, choose disease-free seedlings. For plants that have already been severely affected, they should be cut down in time and burned.

(2) Chemical control For mildly affected plants, irrigate the roots with a 500-fold dilution of 50% vinclozolin or 70% hymexazol for control.

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